Progression Of Osteoporosis Research Articles

In-silico analysis predicts disruption of normal angiogenesis as a causative factor in osteoporosis pathogenesis

Angiogenesis-osteogenesis coupling is critical for proper functioning and maintaining the health of bones. Any disruption in this coupling, associated with aging and disease, might lead to loss of bone mass. Osteoporosis (OP) is a debilitating bone metabolic disorder that affects the microarchitecture of bones, gradually leading to fracture. Computational analysis revealed that normal angiogenesis is disrupted during the progression of OP, especially postmenopausal osteoporosis (PMOP). The genes associated with OP and PMOP were retrieved from the DisGeNET database. Hub gene analysis and molecular pathway enrichment were performed via the Cytoscape plugins STRING, MCODE, CytoHubba, ClueGO and the web-based tool Enrichr. Twenty-eight (28) hub genes were identified, eight of which were transcription factors (HIF1A, JUN, TP53, ESR1, MYC, PPARG, RUNX2 and SOX9). Analysis of SNPs associated with hub genes via the gnomAD, I-Mutant2.0, MUpro, ConSurf and COACH servers revealed the substitution F201L in IL6 as the most deleterious. The IL6 protein was modeled in the SWISS-MODEL server and the substitution was analyzed via the YASARA FoldX plugin. A positive ΔΔG (1.936) of the F201L mutant indicates that the mutated structure is less stable than the wild-type structure is. Thirteen hub genes, including IL6 and the enriched molecular pathways were found to be profoundly involved in angiogenesis/endothelial function and immune signaling. Mechanical loading of bones through weight-bearing exercises can activate osteoblasts via mechanotransduction leading to increased bone formation. The present study suggests proper mechanical loading of bone as a preventive strategy for PMOP, by which angiogenesis and the immune status of the bone can be maintained. This in silico analysis could be used to understand the molecular etiology of OP and to develop novel therapeutic approaches.

Integrated Single-cell RNA-seq and Bulk RNA-seq Identify Diagnostic Biomarkers for Postmenopausal Osteoporosis.

We aimed to explore diagnostic biomarkers of postmenopausal osteoporosis (PMOP). PMOP brings enormous physical and economic burden to elderly women. This study aims to screen new biomarkers for osteoporosis, providing insights for early diagnosis and therapeutic targets of osteoporosis. Weighted gene co-expression network analysis (WGCNA) was applied to identify osteoporosis-related hub genes. Single-cell transcriptomic atlas of osteoporosis was depicted and the heterogeneity of monocytes was analyzed, based on which the biomarkers for osteoporosis were screened. Gene set enrichment analysis (GSEA) was conducted on the biomarkers. The diagnostic model (nomogram) was established and evaluated based on the expression levels of biomarkers. Additionally, the transcription factor (TF) regulatory network was constructed to predict the potential TF and targeted miRNA of biomarkers. The drugs with significant correlation with biomarkers were identified by Spearman correlation analysis. We obtained 30 osteoporosis-associated hub genes. 9 cell types were identified, and the monocytes were subdivided to 4 subtypes. Three biomarkers, DHX29, LSM5, and UBE2V2, were screened. DHX29 and UBE2V2 were highly expressed in non-classical monocytes, while LSM5 exhibited the highest expression in other monocytes, followed by non-classical monocytes. GSEA indicated that osteoporosis may be correlated with vascular calcification and the biomarkers may be involved in the formation of immune cells. Then, nomogram was constructed and exhibited good robustness. In addition, MYC and SETDB1 were the shared IF in three biomarkers, which may play critical regulatory roles in the progression of osteoporosis. Moreover, 41, 49, and 68 drugs appeared significant correlations with DHX29, LSM5, and UBE2V2, respectively. This study provided a basis for early diagnosis and targeted treatment of osteoporosis.

Irg1 regulates bone homeostasis via regulating the Grk5 expression

We have previously demonstrated that itaconic acid can regulate osteoclast differentiation in vitro and in vivo, thereby affecting the progression of osteoporosis. The role of Irg1 as itaconic acid catalytic enzyme in bone homeostasis has not been clearly elucidated. Here, we detected enhanced the osteoclast differentiation in Irg1-deficiency BMMs, along with the expression of genes associated with osteoclastogenesis. Irg1 knockout promoted the expression of Nfatc1 and F-actin ring formation, with the inhibited production of itaconate. RNA-seq analysis was carried out and we proved that Grk5 expression was increased the most. Inhibition of Grk5 attenuated the effect of Irg1 in the osteoclastogenesis. However, micro-CT analysis showed no significant difference of bone trabecular structure in Irg1 knockout mice. Moreover, we observed no significant difference of osteoclasts numbers in the femur of Irg1 knockout mice in vivo. And similar bone formation was detected between the Irg1 knockout and WT mice, indicating that irg1 had slight effect on the bone homeostasis under physiological conditions. Surprising, we detected higher level of inflammatory factors in the bone tissues of Irg1 knockout mice. Above all, we for the first time demonstrated that Irg1 knockout promoted the osteoclastogenesis via regulating the Grk5 signaling. Regulation of irg1-Grk5 axis could be effective in treating human diseases under pathological situations in the future.

Bazi Bushen attenuates osteoporosis in SAMP6 mice by regulating PI3K-AKT and apoptosis pathways.

Osteoporosis (OP), a systemic skeletal disease, is characterized by low bone mass, bone tissue degradation and bone microarchitecture disturbance. Bazi Bushen, a Chinese patented medicine, has been demonstrated to be effective in attenuating OP, but the pharmacological mechanism remains predominantly unclear. In this study, the senescence-accelerated mouse prone 6 (SAMP6) model was used to explore bone homeostasis and treated intragastrically for 9 weeks with Bazi Bushen. Invivo experiments showed that Bazi Bushen treatment not only upregulated the levels of bone mineral density and bone mineral content but also increased the content of RUNX2 and OSX. Furthermore, the primary culture of bone mesenchymal stem cells (BMSCs) in SAMP6 mice was used to verify the effects of Bazi Bushen on the balance of differentiation between osteoblasts and adipocytes, as well as ROS and aging levels. Finally, the pharmacological mechanism of Bazi Bushen in attenuating OP was investigated through network pharmacology and experimental verification, and we found that Bazi Bushen could significantly orchestrate bone homeostasis and attenuate the progression of OP by stimulating PI3K-Akt and inhibiting apoptosis. In summary, our work sheds light on the first evidence that Bazi Bushen attenuates OP by regulating PI3K-AKT and apoptosis pathways to orchestrate bone homeostasis.

Screening of genes co-associated with osteoporosis and chronic HBV infection based on bioinformatics analysis and machine learning.

To identify HBV-related genes (HRGs) implicated in osteoporosis (OP) pathogenesis and develop a diagnostic model for early OP detection in chronic HBV infection (CBI) patients. Five public sequencing datasets were collected from the GEO database. Gene differential expression and LASSO analyses identified genes linked to OP and CBI. Machine learning algorithms (random forests, support vector machines, and gradient boosting machines) further filtered these genes. The best diagnostic model was chosen based on accuracy and Kappa values. A nomogram model based on HRGs was constructed and assessed for reliability. OP patients were divided into two chronic HBV-related clusters using non-negative matrix factorization. Differential gene expression analysis, Gene Ontology, and KEGG enrichment analyses explored the roles of these genes in OP progression, using ssGSEA and GSVA. Differences in immune cell infiltration between clusters and the correlation between HRGs and immune cells were examined using ssGSEA and the Pearson method. Differential gene expression analysis of CBI and combined OP dataset identified 822 and 776 differentially expressed genes, respectively, with 43 genes intersecting. Following LASSO analysis and various machine learning recursive feature elimination algorithms, 16 HRGs were identified. The support vector machine emerged as the best predictive model based on accuracy and Kappa values, with AUC values of 0.92, 0.83, 0.74, and 0.7 for the training set, validation set, GSE7429, and GSE7158, respectively. The nomogram model exhibited AUC values of 0.91, 0.79, and 0.68 in the training set, GSE7429, and GSE7158, respectively. Non-negative matrix factorization divided OP patients into two clusters, revealing statistically significant differences in 11 types of immune cell infiltration between clusters. Finally, intersecting the HRGs obtained from LASSO analysis with the HRGs identified three genes. This study successfully identified HRGs and developed an efficient diagnostic model based on HRGs, demonstrating high accuracy and strong predictive performance across multiple datasets. This research not only offers new insights into the complex relationship between OP and CBI but also establishes a foundation for the development of early diagnostic and personalized treatment strategies for chronic HBV-related OP.

Mechanical impact of regional structural deterioration and tissue-level compensation on proximal femur trabecular bone.

Osteoporosis-induced changes in bone structure and composition significantly reduce bone strength, particularly in the human proximal femur. This study examines how these changes affect the mechanical performance of trabecular bone to enhance diagnosis, prevention, and treatment strategies. A proximal femur sample was scanned using micro-CT at 40μm resolution. Five regions of interest were selected within the femoral head, femoral neck, and greater trochanter. Structural models simulating various stages of osteoporosis were created using image processing software. Micro-finite element analysis evaluated the mechanical properties of trabecular bone under different conditions of structural deterioration and tissue-level elastic modulus variations. The combined effects of structural deterioration and tissue-level mechanical properties on trabecular bone mechanical performance were further analyzed. The mechanical performance of trabecular bone generally follows a power-law relationship with its microstructural characteristics. However, in any specific region, the apparent mechanical properties linearly decrease with structural deterioration. The femoral neck and greater trochanter are more sensitive to structural deterioration than the femoral head. A 5% bone mass loss in the femoral head led to a 7% reduction in mechanical performance, while the femoral neck experienced a 12% loss. Increasing tissue-level elastic modulus improved mechanical performance, partially offsetting bone mass reduction effects. Trabecular bone in low bone mass regions is more affected by bone mass loss. Structural deterioration primarily reduces bone strength, but improvements in tissue-level properties can mitigate this effect, especially in early osteoporosis. Targeted assessments and interventions are crucial for effective management. Future research should explore heterogeneous deterioration models to better understand osteoporosis progression.

Delay the progression of glucocorticoid-induced osteoporosis: Fraxin targets ferroptosis via the Nrf2/GPX4 pathway.

Glucocorticoid-induced osteoporosis (GIOP) commonly accelerates bone loss, increasing the risk of fractures and osteonecrosis more significantly than traditional menopausal osteoporosis. The extracellular environment influenced by glucocorticoids heightens fracture and osteonecrosis risks. Fraxin (Fra), a key component of the traditional Chinese herbal remedy Cortex Fraxini, is known for its wide-ranging pharmacological effects, but its impact on GIOP remains unexplored. This investigation aims to delineate the effects and underlying mechanisms of Fra in combating dexamethasone (Dex)-induced ferroptosis and GIOP. We established a mouse model of GIOP via intraperitoneal injections of Dex and cultured osteoblasts with Dex treatment for in vitro analysis. We evaluated the impact of Fra on Dex-treated osteoblasts through assays such as C11-BODIPY and FerroOrange staining, mitochondrial functionality tests, and protein expression analyses via Western blot and immunofluorescence. The influence of Fra on bone microarchitecture of GIOP in mice was assessed using microcomputerized tomography, hematoxylin and eosin staining, double-labeling with Calcein-Alizarin Red S, and immunohistochemistry at imaging and histological levels. Based on our data, Fra prevented Dex-induced ferroptosis and bone loss. In vitro, glutathione levels increased and malondialdehyde, lipid peroxidation, and mitochondrial reactive oxygen species decreased. Fra treatment also increases nuclear factor erythroid 2-related factor 2 (Nrf2), glutathione peroxidase 4 (GPX4), and COL1A1 expression and promotes bone formation. To delve deeper into the mechanism, the findings revealed that Fra triggered the activation of Nrf2/GPX4 signaling. Moreover, the use of siRNA-Nrf2 blocked the beneficial effect of Fra in osteoblasts cultivated with Dex. Fra effectively combats GIOP by activating the Nrf2/GPX4 signaling pathway to inhibit ferroptosis.

Excessive glucocorticoids combined with RANKL promote the differentiation of bone marrow macrophages (BMM) into osteoclasts and accelerate the progression of osteoporosis by activating the SYK/SHP2/NF-κB signaling pathway.

The primary objective of this study was to explore the extensive implications and complex molecular interactions arising from the confluence of excessive glucocorticoids and RANKL on the differentiation process of BMM into osteoclasts, profoundly impacting osteoporosis development. The methodology encompassed X-ray analysis and HE staining for evaluating bone loss in mice, while immunohistochemical staining was utilized to observe phosphorylated SHP2 (p-SHP2) expression. The assessment of several phosphorylated and total protein expression levels, including NF-κB, SHP2, SYK, JAK2, TAK1, NFATC1, c-fos, and Cathepsin K, was conducted via Western blotting. Additional experiments, involving CCK8 and monoclonal proliferation assays, were undertaken to determine BMM proliferation capacity. Immunofluorescence staining facilitated the quantification of TRAP fluorescence intensity. In vivo analysis revealed that glucocorticoid surplus triggers SHP2 signaling pathway activation, accelerating osteoporosis progression. Western blot results demonstrated that SHP2 inhibition could decrease the expression of specific proteins such as p-NF-κB and p-SHP2, with minimal effects on p-SYK levels. In vitro findings indicated that glucocorticoid and RANKL interaction activates the SHP2 pathway through NF-κB and SYK pathways, enhancing expressions of p-JAK2, p-TAK1, NFATC1, c-fos, and Cathepsin K, thereby promoting BMM to osteoclast transformation. Conclusion: Excessive glucocorticoids and RANKL interaction advance osteoclast differentiation from BMM by activating the SYK/SHP2/NF-κB signaling pathway, expediting osteoporosis progression.

Approach to the Pediatric Patient with Glucocorticoid-Induced Osteoporosis.

Glucocorticoid (GC) therapy remains the cornerstone of treatment for many conditions of childhood and an important cause of skeletal and endocrine morbidity. Here, we discuss cases that bring to life the most important concepts in the management of pediatric GC-induced osteoporosis (pGIO). Given the wide variety of underlying conditions linked to pGIO, we focus on the fundamental clinical-biological principles that provide a blueprint for management in any clinical context. In so doing, we underscore the importance of longitudinal vertebral fracture phenotyping, how knowledge about the timing and risk of fractures influences monitoring, the role of bone mineral density in pGIO assessments, and the impact of growth-mediated "vertebral body reshaping" after spine fractures on the therapeutic approach. Overall, pGIO management is predicated upon early identification of fractures (including vertebral) in those at risk, and timely intervention when there is limited potential for spontaneous recovery. Even a single, low-trauma long bone or vertebral fracture can signal an osteoporotic event in an at-risk child. The most widely used treatments for pediatric osteoporosis, intravenous bisphosphonates, are currently recommended first-line for the treatment of pGIO. It is recognized, however, that even early identification of bone fragility, combined with timely introduction of the most potent bisphosphonate therapies, may not completely prevent osteoporosis progression in all contexts. Therefore, prevention of first-ever fractures in the highest-risk settings is on the horizon, where there is also a need to move beyond anti-resorptives to the study of anabolic agents.

The role of calcium channels in osteoporosis and their therapeutic potential.

Osteoporosis, a systemic skeletal disorder marked by diminished bone mass and compromised bone microarchitecture, is becoming increasingly prevalent due to an aging population. The underlying pathophysiology of osteoporosis is attributed to an imbalance between osteoclast-mediated bone resorption and osteoblast-mediated bone formation. Osteoclasts play a crucial role in the development of osteoporosis through various molecular pathways, including the RANK/RANKL/OPG signaling axis, cytokines, and integrins. Notably, the calcium signaling pathway is pivotal in regulating osteoclast activation and function, influencing bone resorption activity. Disruption in calcium signaling can lead to increased osteoclast-mediated bone resorption, contributing to the progression of osteoporosis. Emerging research indicates that calcium-permeable channels on the cellular membrane play a critical role in bone metabolism by modulating these intracellular calcium pathways. Here, we provide an overview of current literature on the regulation of plasma membrane calcium channels in relation to bone metabolism with particular emphasis on their dysregulation during the progression of osteoporosis. Targeting these calcium channels may represent a potential therapeutic strategy for treating osteoporosis.

An update on the role of ferroptosis in the pathogenesis of osteoporosis.

Ferroptosis is a novel form of programmed cell death, distinguished from apoptosis, autophagy, and programmed necrosis and has received much attention since it was defined in 2012. Ferroptotic cells physiologically exhibit iron metabolism dysregulation, oxidative stress, and lipid peroxidation. Morphologically, they show plasma membrane disruption, cytoplasmic swelling, and mitochondrial condensation. Osteoporosis is taken more and more seriously as the proportion of the aging population continues to increase globally. Interestingly, ferroptosis has been demonstrated to be involved in the development and progression of osteoporosis in many extant studies. The review summarizes iron metabolism, lipid peroxidation, and the different regulatory signals in ferroptosis. Changes in signaling mechanisms within osteoblasts, osteoclasts, and osteocytes after ferroptosis occur are explained here. Studies showed ferroptosis play an important role in different osteoporosis models (diabetes osteoporosis, postmenopausal osteoporosis, glucocorticoid-induced osteoporosis). Inhibitors and EC (Exos) targeting ferroptosis could ameliorate bone loss in osteoporotic mice by protecting cells against lipid peroxidation. Shortly, we hope that more effective and appropriate clinical therapy means will be utilized in the treatment of osteoporosis.

CBP-mediated FOXO4 acetylation facilitates postmenopausal osteoporosis (PMO) progression through the inhibition of the Wnt/β-catenin signaling pathway.

FOXO4 was previously identified as a potential biomarker and therapeutic target for postmenopausal osteoporosis (PMO) using bioinformatic analysis, but its specific function and molecular mechanism in the progression of osteoporosis was not reported. The current study was designed to investigate the biological function and underlying mechanism of FOXO4 in PMO. Our results showed that FOXO4 expression was significantly upregulated in the serum samples of PMO patients, which was also negatively correlated with the expression of osteogenesis genes (OCN and ALP). In addition, FOXO4 depletion alleviated osteoporosis by facilitating osteogenic differentiation and inhibiting adipogenic differentiation in human bone marrow mesenchymal stem cells (hBMSCs). Overexpression of FOXO4 exerted the opposite effects on the osteogenic/adipogenic differentiation in hBMSCs. Moreover, FOXO4 knockdown activated the Wnt/β-catenin signaling whereas the inhibition of Wnt/β-catenin signaling overturned the effects of FOXO4 deficiency on osteoporosis. Furthermore, FOXO4 upregulation in PMO was caused by CBP-induced acetylation. In summary, our data demonstrated that FOXO4 was a potent biomarker for PMO and mediated the balance between osteogenesis and adipogenesis in hBMSCs by regulating Wnt/β-catenin signaling.

Osteoclast-derived exosomes influence osteoblast differentiation in osteoporosis progression via the lncRNA AW011738/ miR-24-2-5p/ TREM1 axis

AimsTo investigate the molecular mechanism of osteoclast-derived exosomes in osteoporosis. Main methodsRANKL induced osteoclast model was screened for significantly differentially expressed lncRNAs and mRNAs by whole RNA sequencing. Exosomes were characterized using electron microscopy, western blotting and nanosight. Overexpression or knockdown of AW011738 was performed to explore its function. The degree of osteoporosis in an osteoporosis model was assessed by mirco-CT. The osteoclast model, osteoblast differentiation ability and the molecular mechanism of lncRNA AW011738/miR-24-2-5p/TREM1 axis in osteoporosis were assessed by dual luciferase reporter gene assay, Western blotting (WB), immunofluorescence and ALP staining. Bioinformatics was used to predict interactions of key osteoporosis-related genes with miRNAs, transcription factors, and potential drugs after upregulation of AW011738. To predict the protein-protein interaction (PPI) network associated with key genes, GO and KEGG analyses were performed on the key genes. The ssGSVA was used to predict changes in the immune microenvironment. Key findingsOsteoclast-derived exosomes containing lncRNA AW011738 decreased the osteogenesis-related markers and accelerated bone loss in OVX mice. Osteoclast (si-AW011738)-derived exosomes showed a significant increase in biomarkers of osteoblast differentiation in vitro compared to the si-NC group. As analyzed by mirco-CT, tail vein injected si-AW011738 OVX mice were less osteoporotic than the control group. AW011738 inhibited osteoblast differentiation by regulating TREM1 expression through microRNA. Meanwhile, overexpression of miR-24-2-5p inhibited TREM1 expression to promote osteoblast differentiation. SignificanceOsteoclast-derived exosomes containing lncRNA AW011738 inhibit osteogenesis in MC3T3-E1 cells through the lncRNA AW011738/miR-24-2-5p/TREM1 axis and exacerbate osteoporosis in OVX mice.

Based on NF-κB and Notch1/Hes1 Signaling Pathways, the Mechanism of Artesunate on Inflammation in Osteoporosis in Ovariectomized Rats was Investigated.

Artesunate (ART) has the potential to modulate the nuclear factor kappa B (NF-κB) and Notch1/Hes1 signaling pathways, which play crucial roles in the pathogenesis of osteoporosis. This study aims to explore whether ART participates in the progression of osteoporosis by regulating these signaling pathways. In the in vitro experiments, we treated bone marrow mesenchymal stem cells (BMSCs) with different concentrations of ART (0, 3, 6, 12 µM) and evaluated osteogenic differentiation using alkaline phosphatase staining (ALP) and alizarin red S staining (ARS) staining. The expression levels of osteocalcin (OCN), RUNT-related transcription factor 2 (RUNX2), osteoprotegerin (OPG), and receptor activator of the nuclear factor kappa ligand (RANKL) were detected by real-time quantitative PCR (RT-qPCR). The effects of ART on NF-κB p65 and Notch1 protein expression were analyzed by Western blot (WB) and immunofluorescence (IF). In the in vivo experiments, a postmenopausal osteoporosis rat model was established via ovariectomy. Bone tissue pathological injury was evaluated using hematoxylin eosin (HE) staining. Serum ALP levels were measured using a kit, bone density was determined by dual-energy X-ray absorptiometry, and serum levels of bone gla protein (BGP), OPG, RANKL, tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), and IL-1β were measured by enzyme-linked immunosorbent assay (ELISA). Additionally, the expression of NF-κB p65 and Notch1 in tissues was assessed by immunohistochemistry. In vitro experiments revealed that compared to the control group, ART dose-dependently promoted BMSCs proliferation and enhanced their osteogenic differentiation capability. The expression of OCN, RUNX2, and OPG significantly increased in the ART-treated group, while RANKL expression decreased significantly (p < 0.05). ART significantly inhibited the expression of NF-κB p65 and Notch1/Hes1 signaling pathway proteins (p < 0.05). Compared to ART treatment alone, combined treatment with ART and phorbol myristate acetate (PMA) or valproic acid (VPA) resulted in increased expression of NF-κB p65 and Notch1 proteins and decreased osteogenic differentiation capability (p < 0.05). In vivo experiments showed that in rats treated with ART, bone damage was significantly reduced, bone density and mineral content were restored considerably, and the expression of inflammatory factors (TNF-α, IL-6, IL-1β) decreased significantly (p < 0.05). Additionally, ART treatment significantly reduced the expression of NF-κB p65 and Notch1 proteins, increased OPG expression, and decreased BGP and RANKL levels (p < 0.05). In summary, ART facilitates the osteogenic differentiation of BMSCs by inhibiting the NF-κB and Notch1/Hes1 signaling pathways, thereby exerting significant protective effects against osteoporosis.

SP1 regulates BMSC osteogenic differentiation through the miR-133a-3p/MAPK3 axis

BackgroundThe progression of osteoporosis (OP) can dramatically increase the risk of fractures, which seriously disturb the life of elderly individuals. Specific protein 1 (SP1) is involved in OP progression. However, the mechanism by which SP1 regulates OP progression remains unclear.ObjectiveThis study investigated the mechanism underlying the function of SP1 in OP.MethodsSAMP6 mice were used to establish an in vivo model of age-dependent OP, and BALB/c mice were used as controls. BMSCs were extracted from two subtypes of mice. Hematoxylin and eosin staining were performed to mark the intramedullary trabecular bone structure to evaluate histological changes. ChIP assay was used to assess the targeted regulation between SP1 and miR-133a-3p. The binding sites between MAPK3 and miR-133a-3p were verified using a dual-luciferase reporter assay. The mRNA levels of miR-133a-3p and MAPK3 were detected using quantitative reverse transcription polymerase chain reaction (RT-qPCR). The protein expression of SP1, MAPK3, Colla1, OCN, and Runx2 was examined using Western blotting. Alkaline phosphatase (ALP) kit and Alizarin Red S staining were used to investigate ALP activity and mineralized nodules, respectively.ResultsThe levels of SP1 and miR-133a-3p were upregulated, whereas the expression of MAPK3 was downregulated in BMSCs from SAMP6 mice, and miR-133a-3p inhibitor accelerated osteogenic differentiation in BMSCs. SP1 directly targeted miR-133a-3p, and MAPK3 was the downstream mRNA of miR-133a-3p. Mechanically, SP1 accelerated osteogenic differentiation in BMSCs via transcriptional mediation of the miR-133a-3p/MAPK3 axis.ConclusionSP1 regulates osteogenic differentiation by mediating the miR-133a-3p/MAPK3 axis, which would shed new light on strategies for treating senile OP.

Mitochondria from osteolineage cells regulate myeloid cell-mediated bone resorption

Interactions between osteolineage cells and myeloid cells play important roles in maintaining skeletal homeostasis. Herein, we find that osteolineage cells transfer mitochondria to myeloid cells. Impairment of the transfer of mitochondria by deleting MIRO1 in osteolineage cells leads to increased myeloid cell commitment toward osteoclastic lineage cells and promotes bone resorption. In detail, impaired mitochondrial transfer from osteolineage cells alters glutathione metabolism and protects osteoclastic lineage cells from ferroptosis, thus promoting osteoclast activities. Furthermore, mitochondrial transfer from osteolineage cells to myeloid cells is involved in the regulation of glucocorticoid-induced osteoporosis, and glutathione depletion alleviates the progression of glucocorticoid-induced osteoporosis. These findings reveal an unappreciated mechanism underlying the interaction between osteolineage cells and myeloid cells to regulate skeletal metabolic homeostasis and provide insights into glucocorticoid-induced osteoporosis progression.

The Role of MicroRNAs in the Pathophysiology of Osteoarthritis.

Worldwide, osteoarthritis (OA) is the most common cause of joint pain in older people. Many factors contribute to osteoarthritis' development and progression, including secondary osteoarthritis' underlying causes. It is important to note that osteoarthritis affects all four tissues: cartilage, bone, joint capsule, and articular apparatus. An increasingly prominent area of research in osteoarthritis regulation is microRNAs (miRNAs), a small, single-stranded RNA molecule that controls gene expression in eukaryotes. We aimed to assess and summarize current knowledge about the mechanisms of the action of miRNAs and their clinical significance. Osteoarthritis (OA) is affected by the interaction between miRNAs and inflammatory processes, as well as cartilage metabolism. MiRNAs also influence cartilage cell apoptosis, contributing to the degradation of the cartilage in OA. Studies have shown that miRNAs may have both an inhibitory and promoting effect on osteoporosis progression through their influence on molecular mechanisms. By identifying these regulators, targeted treatments for osteoarthritis may be developed. In addition, microRNA may also serve as a biomarker for osteoarthritis. By using these biomarkers, the disease could be detected faster, and early intervention can be instituted to prevent mobility loss and slow deterioration.

XAF1 promotes osteoclast apoptosis by antagonizing the XIAP-caspase axis

BackgroundOver-activated osteoclast (OC) is a major cause of diseases related to bone loss and bone metabolism. Both bone resorption inhibition and apoptosis induction of osteoclast are crucial in treating these diseases. X-linked inhibitor of apoptosis protein (XIAP)-associated factor 1 (XAF1) is an important interferon-stimulated and apoptotic gene. However, how XAF1 regulates bone formation and remodeling is unknown. MethodsWe generate global and chimeric Xaf1 knockout mouse models and utilize these models to explore the function and mechanism of XAF1 in regulating bone formation and remodeling in vivo and in vitro. ResultsWe show that XAF1 depletion enhances osteoclast generation in vitro. XAF1 knockout increases osteoclast number and bone resorption, thereby exacerbating bone loss in both OVX and osteolysis models. Activation of XAF1 with BV6 (a potent XIAP inhibitor) suppresses osteoclast formation. Mechanistically, XAF1 deletion decreases osteoclast apoptosis by facilitating the interaction between XIAP and caspase-3/7. ConclusionsOur data illustrates an essential role of XAF1 in controlling osteoclastogenesis in both osteoporosis and osteolysis mouse models and highlights its underlying mechanism, indicating a potential role in clinical treatment.The translational potential of this article: The translation potential of this article is that we first indicated that osteoclast apoptosis induced by XAF1 contribute to the progression of osteoporosis and osteolysis, which provides a novel strategy in the prevention of osteoporosis and osteolysis.

The role of magnesium in the pathogenesis of osteoporosis.

Magnesium (Mg), a nutritional element which is essential for bone development and mineralization, has a role in the progression of osteoporosis. Osteoporosis is a multifactorial disease characterized by significant deterioration of bone microstructure and bone loss. Mg deficiency can affect bone structure in an indirect way through the two main regulators of calcium homeostasis (parathyroid hormone and vitamin D). In human osteoblasts (OBs), parathyroid hormone regulates the expression of receptor activator of nuclear factor-κ B ligand (RANKL) and osteoprotegerin (OPG) to affect osteoclast (OC) formation. In addition, Mg may also affect the vitamin D3 -mediated bone remodeling activity. vitamin D3 usually coordinates the activation of the OB and OC. The unbalanced activation OC leads to bone resorption. The RANK/RANKL/OPG axis is considered to be a key factor in the molecular mechanism of osteoporosis. Mg participates in the pathogenesis of osteoporosis by affecting the regulation of parathyroid hormone and vitamin D levels to affect the RANK/RANKL/OPG axis. Different factors affecting the axis and enhancing OC function led to bone loss and bone tissue microstructure damage, which leads to the occurrence of osteoporosis. Clinical research has shown that Mg supplementation can alleviate the symptoms of osteoporosis to some extent.

Pyroptosis mediates osteoporosis via the inflammation immune microenvironment.

Osteoporosis represents a systemic imbalance in bone metabolism, augmenting the susceptibility to fractures among patients and emerging as a notable mortality determinant in the elderly population. It has evolved into a worldwide concern impacting the physical well-being of the elderly, imposing a substantial burden on both human society and the economy. Presently, the precise pathogenesis of osteoporosis remains inadequately characterized and necessitates further exploration. The advancement of osteoporosis is typically linked to the initiation of an inflammatory response. Cells in an inflammatory environment can cause inflammatory death including pyroptosis. Pyroptosis is a recently identified form of programmed cell death with inflammatory properties, mediated by the caspase and gasdermin families. It is regarded as the most inflammatory form of cell death in contemporary medical research. Under the influence of diverse cytokines, macrophages, and other immune cells may undergo pyroptosis, releasing inflammatory factors, such as IL-1β and IL-18. Numerous lines of evidence highlight the pivotal role of pyroptosis in the pathogenesis of inflammatory diseases, including cancer, intestinal disorders, hepatic conditions, and cutaneous ailments. Osteoporosis progression is frequently associated with inflammation; hence, pyroptosis may also play a role in the pathogenesis of osteoporosis to a certain extent, making it a potential target for treatment. This paper has provided a comprehensive summary of pertinent research concerning pyroptosis and its impact on osteoporosis. The notion proposing that pyroptosis mediates osteoporosis via the inflammatory immune microenvironment is advanced, and we subsequently investigate potential targets for treating osteoporosis through the modulation of pyroptosis.